A flow cytometer is useful for identifying particles and characteristics of particles contained within a fluid. The fluid is typically passed through a small nozzle that generates a narrow fluid stream. A laser beam illuminates the particles in the fluid stream as they pass. Detectors are positioned to detect light transmission and scatter. This information is then used by the flow cytometer to identify the particles and characteristics of the particles in the fluid.
A sorting flow cytometer uses information about the particles to sort the particles into different containers. To do so, the fluid stream is divided into a series of individual drops containing one or more of the particles. Each drop containing one or more particles to be sorted is given an electrical charge based on the particle characteristics. The drops are then passed between oppositely charged deflection plates. Positively charged drops are displaced toward the negatively charged plate, while negatively charged drops are displaced toward the positively charged plate. The larger the charge, the greater the displacement of the drop. The drops are sorted into multiple different containers arranged below and between the plates.